Embodiments of the present disclosure relate to communication of signals, and more particularly to the inductive communication of signals in an imaging system.
In just a few decades, the use of magnetic resonance imaging (MRI) scanners has grown tremendously. MRI scans are being increasingly used to aid in the diagnosis of multiple sclerosis, brain tumors, torn ligaments, tendonitis, cancer, strokes, and the like. As will be appreciated, MRI is a noninvasive medical test that aids physicians in the diagnoses and treatment of various medical conditions. The enhanced contrast that an MRI scan provides between the different soft tissues of the body allows physicians to better evaluate the various parts of the body and determine the presence of certain diseases that may not be assessed adequately with other imaging methods such as X-ray, ultrasound, or computed tomography (CT).
An MRI system typically includes one or more coils to generate the magnetic field. Additionally, the MRI system also includes one or more MRI receiver coils configured to detect signals from a gyromagnetic material within a patient. These MRI receiver coil arrays typically entail use of bulky cables. Use of these bulky cables increases the difficulty in situating the receiver coils over the patient before the scanning procedure. Furthermore, the advent of parallel imaging has led to the increase in the number of MRI receiver channels. Unfortunately, this increase in the number of receiver channels has further exacerbated the problem with a corresponding increase in the number of bulky cables.
Some currently available techniques call for embedding a subset of the coils in the cradle underneath the patient. However, each coil is attached to a preamplifier, a cable, and baluns, all of which must be accommodated in the cradle. Cables also increase the weight of the anterior arrays that are positioned on the patient, thereby causing discomfort to the patient. Moreover, the cables also increase time and complexity of the scanning procedure, with decreased patient throughput as these cables need to be plugged in and connections need to be verified prior to the scanning procedure. In addition, these techniques may also call for the use of a switch or a multiplexer to connect different subsets of coils to receiver electronics as different portions of the anatomy are scanned.
Certain other demonstrated techniques entail the use of microwave or optical links to acquire signals without the use of cables. In these methods, the signal from each coil is amplified and then converted to an optical or microwave signal which is then beamed through space to a receiver in the scanner bore or outside the bore. The signal may or may not be demodulated to a different frequency and/or digitized before conversion. However, these signal conversions require placement of additional circuits on the coils, which can substantially increase the amount of power required by the coils, and lead to increased heat generation on the coils. The additional circuitry can also add to the weight and bulk of the coil arrays, and can potentially interfere with the radiofrequency (RF) fields being detected by the coils.
Moreover, some other currently available techniques call for positioning a posterior array at a fixed location under the cradle. Although these methods reduce the number of coils and associated hardware, these methods can result in significant loss in signal-to-noise ratio (SNR). Additionally, certain other demonstrated techniques inductively couple the receive coils to anterior arrays using patient-bed coupling elements that are attached to the local imaging coils by internal cabling, and are inductively coupled to base coupling elements positioned at the sides of the cradle. However, the relatively large size of the coupling elements and the limited space at the side of the cradle limit the versatility of this approach, thereby making it hard to use these techniques with large arrays. In other techniques, the sniffer coils are fixedly coupled to the imaging system, thereby reducing the flexibility of the system during the scanning procedure. Also, induced voltages can lead to patient heating.